Palindrome Golf

Answer 1

Groovy 17B:

p={it==it[-1..0]}

Downside is that it doesn't work with emptry string.

On second thought, throwing exception for empty string is reasonable since you can't tell if nothing is palindrome or not.

Answer 2

Perl (27 chars):

sub p{$_[0]eq reverse$_[0]}

Ruby (24 chars):

def p(a)a==a.reverse end

Answer 3

Common Lisp, short-and-cheating version (23 chars):

#L(equal !1(reverse !1))

#L is a reader macro character implemented by SHARPL-READER in the iterate package. It's basically equivalent to (lambda (!1) ...).

Common Lisp, long version using only primitives (137 including whitespace, compressible down to 108):

(defun p (s)
  (let ((l (1- (length s))))
    (iter (for i from l downto (/ l 2))
          (always (equal (elt s i) (elt s (- l i)))))))

Again, it uses iterate, which is basically a cleaner version of the builtin LOOP facility, so I tend to treat it as being in the core language.

Answer 4

Clojure using 37 characters:

user=> (defn p[s](=(seq s)(reverse(seq s))))
#'user/p
user=> (p "radar")
true
user=> (p "moose")
false

Answer 5

Not the shortest, and very after-the-fact, but I couldn't help giving it a try in MATLAB:

R=@(s)all(s==fliplr(s));

24 chars.

Answer 6

C# Without Reverse Function 84 chars

int p(char[]s){int i=0,l=s.Length,t=1;while(++i<l)if(s[i]!=s[l-i-1])t&=0;return t;} 

C# Without Reverse Function 86 chars

int p(char[]s){int i=0;int l=s.Length;while(++i<l)if(s[i]!=s[l-i-1])return 0;return 1;}

VBScript 41 chars

function p:p=s=strreverse(s):end function